quiet as stock stainless muffler? suggestions?

[chevybuilder18]

The thrush mufflers i have had before i painted chevy orange. i didnt take chances of these rusting. stainless steel can rust too. the paint i used was the rustoilium chevy orange high temp paint. they were pretty sharp after wards but the i noticed there was a flange that was on both sides of the mufflers inlets or outlets (universal imput or output mufflers) so i took a rotary tool and grinding stone and did some grinding on the inside of the muffler on this lip, which you can see by looking inside these mufflers. sounds crazy, but i only did one side so restriction was one way. exhaust entered with no problem, and back pressure isnt a problem. buddy of mine is now running these on his van, gets good gas mileage and noise isnt a problem